Comparison of Various Turbulence Models for Violent Geysers in Vertical Pipes

Four frequently used turbulence models, namely k-ε, realizable k-ε, k-ω, and SST k-ω have been used for simulating violent geysers in vertical pipes. The simulations have been performed using OpenFOAM and the assessment of the adopted models has been carried out by comparing the results with a set of experimental data from the literature. The quantities compared are pressure traces at certain locations, geyser height, and snapshots in the horizontal and vertical pipes at various stages during the geysering. The comparison of turbulence models suggests that all of these models predict almost the same geyser height with a difference of less than 2%. Pressure fluctuations predicted by realizable k-ε and SST k-ω models, however, are in better agreement with the data. Additionally, comparison of experimental and numerical snapshots reveals that the flow patterns obtained using the realizable k-ε model matches those of the experiments more closely. Regarding the computation time, k-ε model outperformed other models, as CPU times of k-ω, SST k-ω, and realizable k-ε models were 1.5, 1.2, and 1.1 times that of k-ε model, respectively.